I've had a lovely week on holiday down in London with the family, being proper tourists. Under the dreich weather of Monday we ventured Thames-side and towards the terrifying but fun seethrough walkways of Tower Bridge. Along the side of the walkways were photographs of some of the world's great bridges, together with some of the history about how this iconic bridge came to be.
What did we learn?
This landmark, required to cope with the overwhelming population growth on either side of the river and increased river traffic to the upper parts of the Thames, was borne out of many, mostly failed, prototypes, most in the form of sketches.
Thank goodness we didn't stop at the first prototypes submitted to the public competition. The dual lock system would hardly have helped with the drastically increasing river traffic of the industrial revolution:
And a system of hydraulic elevators would have failed in the other sense, not really foreseeing 2015's automotive traffic needing a quick north-south crossing:
Some designers simply did without a bridge and went for the tunnel - perfect for traffic throughput in the longer term and not disruptive at all to the river traffic. In the end, though, it was feasibility that killed these tunnel ideas off - the runways required to descend human and horse-drawn traffic into them were so long that they ate up most of the land either side of the river:
As the final designer was chosen, even his first drafts were off the mark on the aesthetic side:
In the end, the rules for killing ideas and honing the kernels of interesting ideas down haven't changed since the bridge's completion in 1894 and today, as I describe them in my book: desirability (do they want or need it?), feasibility (can we do it?) and viability (should we do it?).
The result, is an imperfect perfection that we recognise in an instant: